Surgical instrument with a separable coaxial joint

ABSTRACT

A surgical instrument includes an elongated shaft having a proximal structural member and a proximal drive member that is selectively movable with respect to the proximal structural member. A modular end effector is removably coupled to the elongated shaft, and has a distal structural member and a distal drive member that is operatively coupled to a pair of jaw members. A separable joint is defined between the elongated shaft and the end effector. The separable joint includes laterally prominent and laterally indented portions of each of the proximal and distal structural members and of each of the proximal and distal drive members. The structural members are interlocked to resist longitudinal separation and permit lateral separation. The drive members are movable relative to structural members to move the separable joint to a locked configuration wherein the drive members prohibit lateral separation of the structural members.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/691,940 filed Apr. 21, 2015, now U.S. Pat. No. 10,278,769, which is adivisional of U.S. patent application Ser. No. 12/822,024 filed on Jun.23, 2010, now U.S. Pat. No. 9,028,495, the entire contents of each whichare hereby incorporated by reference.

BACKGROUND Technical Field Separable

The present disclosure relates generally the field of reposable orreusable surgical instruments. In particular, the disclosure relates toinstruments having separable and replaceable components to provideclean, sterile or refurbished surfaces in each instance of use.

Background of Related Art

Instruments such as electrosurgical forceps are commonly used in openand endoscopic surgical procedures to coagulate, cauterize and sealtissue. Such forceps typically include a pair of jaws that can becontrolled by a surgeon to grasp targeted tissue, such as, e.g., a bloodvessel. The jaws may be approximated to apply a mechanical clampingforce to the tissue, and are associated with at least one electrodesurface to permit the delivery of electrosurgical energy to the tissue.The combination of the mechanical clamping force and the electrosurgicalenergy has been demonstrated to join adjacent layers of tissue capturedbetween the jaws. When the adjacent layers of tissue include the wallsof a blood vessel, sealing the tissue may result in hemostasis.Thereafter, the sealed tissue may be transected by advancing a knifethrough the jaws. A detailed discussion of the use of an electrosurgicalforceps may be found in U.S. Pat. No. 7,255,697 to Dycus et al.

In use, various tissue-contacting components of an electrosurgicalforceps tend to become contaminated or degraded. For example, electrodesmay become contaminated as portions of the treated tissue adhere to thetissue-contacting surfaces of the electrodes. Also, a knife blade maybecome dull and less effective in transecting sealed tissue afterrepeated use. In order to provide clean electrodes and a sharp knife fora particular surgical procedure, a brand new instrument is often used.Once the procedure is complete, the used instrument is discarded.

Instruments that may be reused for multiple procedures reduce theinstrumentation costs per procedure. Some reusable forceps include areusable base component adapted for persistent use and a removable andreplaceable modular component adapted for limited use coupled thereto.The reusable base component may include, for example, a control elementsuch as a handle that remains primarily outside the surgical field. Thehandle may be constructed ruggedly to sustain regular and recurringusage in numerous surgical procedures. The removable and replaceablecomponent may include a tool element, such as an end effector containingthe delicate and tissue-contacting wear surfaces. Replacing a worn endeffector to refurbish an instrument provides refreshed surfaces withminimal waste.

Providing replaceable components for a reusable electrosurgical forceps,however, presents various challenges. For example, many of theseinstruments require arduous disassembly and reassembly procedures toensure proper mechanical and electrical connections are made between thereusable and replaceable components.

SUMMARY

The present disclosure describes a reusable surgical instrument fortreating tissue. The instrument includes a handle assembly supporting afirst actuator. An elongated shaft extends distally from the handleassembly and defines a longitudinal axis. The elongated shaft includes aproximal structural member and a proximal drive member, and the proximaldrive member is operatively coupled to the first actuator such thatmanipulation of the first actuator induces movement of the proximaldrive member relative to the proximal structural member. A modular endeffector is removably coupled to the elongated shaft, and includes adistal structural member and a distal drive member. The distal drivemember is operatively coupled to a pair of jaw members such thatmovement of the distal drive member relative to the distal structuralmember induces movement of the jaw members between an open configurationwherein the jaw members are substantially spaced to a closedconfiguration wherein the jaw members are closer together. A separablejoint is defined between the elongated shaft and the end effector. Theseparable joint includes a laterally prominent portion and a laterallyindented portion defined on each of the proximal and distal structuralmembers and configured to interlock with one another such that theproximal and distal structural members resist longitudinal separationand permit separation in a lateral direction. Laterally prominentportions and a laterally indented portions defined on the proximal anddistal drive members are configured to interlock with one another suchthat the proximal and distal drive members transmit motion therebetweenand permit separation in the at least one lateral direction. The drivemembers are movable relative to the structural members to move theseparable joint between a locked configuration wherein the drive membersprohibit separation of the structural members and an unlockedconfiguration wherein the drive members permit separation of thestructural members in the lateral direction.

The structural members may define a generally tubular configurationabout the longitudinal axis, and the drive members may becoaxially-arranged with respect to the structural members. The firstactuator may be operable to induce longitudinal motion in the drivemembers to move the jaw members between the first and secondconfigurations. The handle assembly may also support a second actuator,and the second actuator may be operable to induce rotational motion ofthe drive members to rotate the jaw members about the longitudinal axis.

The end effector may include a knife selectively movable through the jawmembers, and the separable joint may include separable and interlockingportions of a distal knife rod and a proximal knife rod. The distalknife rod may be operatively coupled to the knife to move the knifethrough the jaw members, and the proximal knife rod selectively movablewith respect to the structural members from the handle assembly.

The end effector may include an electrode configured for deliveringelectrosurgical energy to tissue, and the separable joint may includefirst and second electrical connectors. The first electrical connectormay be supported by the elongated shaft and may be electrically coupledto a source of electrosurgical energy. The second electrical connectormay be supported by the end effector and electrically coupled to the atleast one electrode. The first and second electrical connectors may beconfigured to engage and disengage one another in the lateral directionin which the structural members are separable.

The interlocking portions of the structural members may define a firstouter diameter. The distal structural member may be coupled to the endeffector by a shaft portion defining a second outer diameter that issmaller than the first outer diameter.

According to another aspect of the disclosure, a method of assembling asurgical instrument includes the steps of providing the instrument withthe end effector separated from the elongated shaft. Next, the elongatedshaft and the end effector may be approximated in a lateral direction tosimultaneously engage the proximal structural member with the distalstructural member, and the proximal drive member with the distal drivemember. Finally, the first actuator may be manipulated to move the drivemembers into a longitudinal position wherein the drive members prohibitseparation of the structural members in the lateral direction.

According to another aspect of the disclosure, a surgical instrumentincludes a handle assembly supporting an actuator. A proximal tubularmember extends distally from the handle assembly and defines alongitudinal axis. The proximal tubular member includes aninter-engaging mating portion at a distal end thereof. A proximal drivemember extends through the proximal tubular member and is operativelycoupled to the actuator such that manipulation of the actuator induceslongitudinal movement of the proximal drive member relative to theproximal tubular member. The proximal drive member includes aninter-engaging mating portion at a distal end thereof. An end effectorincludes a movable end effector element adapted for moving between firstand second configurations for manipulating tissue. A distal tubularmember extends proximally from the end effector, and includes aninter-engaging mating portion at a proximal end thereof corresponding tothe inter-engaging mating portion of the proximal tubular member. Adistal drive member extends through the distal tubular member. Thedistal drive member is operatively coupled to the movable end effectorelement such that longitudinal movement of the distal drive memberinduces the movable end effector element to move between the first andsecond configurations. The distal drive member includes aninter-engaging mating portion at a proximal end thereof corresponding tothe inter-engaging mating portion of the proximal drive member. Theproximal drive member is movable from an unlocked configuration whereinthe inter-engaging mating portion of the proximal drive member isgenerally aligned with the inter-engaging mating portion of the proximaltubular member to permit lateral engagement and disengagement of theinter-engaging mating portions of the tubular members and drive memberssimultaneously, and a locked configuration wherein the inter-engagingmating portion of the proximal drive member is longitudinally displacedwith respect to the inter-engaging mating portion of the proximaltubular member. In the locked configuration, the proximal drive memberis within one of the proximal and distal tubular members such thatlateral disengagement of the inter-engaging mating portions of thetubular members and drive members is prohibited.

The movable end effector element may include a pair of jaw membersmovable between an open configuration wherein the jaw members aresubstantially spaced to a closed configuration wherein the jaw membersare closer together. Each of the inter-engaging mating portions of thetubular members may include a laterally prominent hook portion and alaterally indented portion for receiving the hook portion of theinter-engaging mating portion of the other tubular member.

The actuator may be operable to move the proximal drive member betweenthe locked and unlocked configurations, and to move the movable endeffector element between the first and second configurations. The endeffector may include an electrode disposed thereon adapted fordelivering electrosurgical energy to tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the presentdisclosure and, together with the detailed description of theembodiments given below, serve to explain the principles of thedisclosure.

FIG. 1 is a perspective view of an endoscopic surgical instrument inaccordance with the present disclosure having a modular end effectorremovably coupled to a distal end of an elongated shaft by a separablecoaxial joint;

FIG. 2 is an enlarged, side view of the end effector of FIG. 1 depictinga pair of jaw members in an open configuration;

FIG. 3 is an enlarged, cross-sectional view of the end effectordepicting the jaw members in a closed configuration, and a reciprocatingknife in a retracted position;

FIG. 4 is a perspective view of an underside of the distal end of theelongated shaft defining a first mating component of the separablecoaxial joint;

FIG. 5 is a side view of the modular end effector defining a secondmating component separated from the first mating component of theseparable coaxial joint in a lateral direction;

FIG. 6 is a side view of the first and second mating components of theseparable coaxial joint adjacent one another in an unlockedconfiguration wherein the first and second mating components may beseparated in the lateral direction;

FIG. 7A is a side view of the first and second mating components of theseparable coaxial joint adjacent one another in a locked configurationwherein the first and second mating components resist separation in thelateral direction;

FIG. 7B is a side view of the first and second mating components in analternate locked configuration; and

FIG. 8 is a sectional, perspective view of an alternate embodiment of aseparable coaxial joint in a locked configuration.

DETAILED DESCRIPTION

Referring initially to FIG. 1, an embodiment of an electrosurgicalinstrument 10 is depicted. The instrument 10 includes a handle assembly12, a modular end effector 14 and an elongated shaft 16 therebetweendefining a longitudinal axis A-A. A surgeon may manipulate the handleassembly 12 to remotely control the end effector 14 through theelongated shaft 16. This configuration is typically associated withinstruments for use in laparoscopic or endoscopic surgical procedures.Various aspects of the present disclosure may also be practiced withtraditional open instruments and in connection with endoluminalprocedures as well.

The instrument 10 is coupled to a source of electrosurgical energy,e.g., an electrosurgical generator 18. The generator 18 may includedevices such as the LIGASURE® Vessel Sealing Generator and the ForceTriad® Generator as sold by Covidien. A cable 20 extends between thehandle assembly 12 and the generator 18, and includes a connector 22 forcoupling the instrument 10 to the generator 18. The connector 22includes two prong members 22 a and 22 b that are dimensioned tomechanically and electrically connect the instrument 10 to oppositepoles (+), (−) associated with the generator 18. Thus, bipolar energymay be provided through the instrument 10. Alternatively, the instrument10 may be configured for delivering monopolar energy to the tissue. In amonopolar configuration, the instrument 10 delivers electrosurgicalenergy of a first potential, e.g. (+), while a return pad (not shown) isplaced generally beneath a patient and provides a return path to theopposite pole, e.g. (−), of the generator 18. A footswitch (not shown)may be provided to initiate and terminate the delivery ofelectrosurgical energy to the end effector 14.

To control movement of the end effector 14, the handle assembly 12includes various actuators that may be manipulated by a surgeon during asurgical procedure. The actuators include a stationary handle 24 andmovable handle 26 that may be separated and approximated relative to oneanother, in the direction of arrows “B0,” to respectively open and closea pair of jaw members 32, 34 in the direction of arrows “B1.” A surgeonmay also rotate a rotation knob 36 about the longitudinal axis A-A inthe direction of arrows “C0” to rotate the end effector 14 about thelongitudinal axis A-A in the direction of arrows “C1.” The embodimentdepicted in FIG. 1 may be considered a “tip rotation” embodiment sincemanipulation of the rotation knob 36 induces rotation only at the distal“tip” of the elongated shaft 16, e.g., only the end effector 14. Asdescribed in greater detail below, the rotation knob 36 is coupled tointerior components of the elongated shaft 16 to cause the end effector14 to rotate. The outermost components of the elongated shaft 16 remainstationary relative to the stationary handle 24. Other embodiments arecontemplated in which the outermost components of the elongated shaft 16may be induced to rotate. These embodiments may be considered “shaftrotation” embodiments. A more detailed discussion of a “shaft rotation”instrument may be found in the above mentioned U.S. Pat. No. 7,255,697to Dycus et al.

Another actuator provided on the handle 12 is trigger 38. Trigger 38 ismovable relative to the stationary handle 24 in the direction of arrows“D0,” and is operable to extend and retract a knife 40 (FIG. 3) throughthe end effector 14 in the direction of arrows “D1.” Each of thesesactuators is mechanically coupled to the end effector 14 through theelongated shaft 16 as described in greater detail below.

A separable coaxial joint 100 is defined between the end effector 14 andthe elongated shaft 16. The joint 100 permits the end effector 14 to beremoved from the elongated shaft 16 such that a new or refurbished endeffector (not shown) may be coupled to the elongated shaft 16 followinga surgical procedure. The handle assembly 12 may be subsequently reusedwith the new or refurbished end effector. As described in greater detailbelow, the joint 100 includes a first mating component 102 a defined ata distal end of the elongated shaft 16 and a second mating component 102b defined at a proximal end of the end effector 14. The first and secondmating components 102 a and 102 b provide electrical connections tooperatively couple the end effector 14 to the generator 18 and themechanical connections to operatively couple the end effector 14 to theactuators, e.g., movable handle 26, rotation knob 36 and trigger 38. Thejoint 100 provides a positive mechanical connection between the endeffector 14 and the elongated shaft 16 such that the end effector 14will not inadvertently be detached during a surgical procedure.

Referring now to FIG. 2, end effector 14 is depicted in an openconfiguration wherein upper and lower jaw members, 32 and 34respectively, are substantially spaced from one another. In the openconfiguration, the jaw members 32, 34 may be maneuvered into position tocapture tissue therebetween. To facilitate maneuvering the end effector14 into position, the end effector 14 may be rotated about longitudinalaxis A-A with respect to an outer tubular member 104 of the secondmating component 102 b. The outer tubular member 104 thus provides adistal stationary reference structure for various relative motions ofthe end effector 14. The end effector 14 is operatively coupled to therotation knob 36 (FIG. 1) through the through separable coaxial joint100 as described below with reference to FIGS. 4 through 7B.

Each of the jaw members 32, 34 is coupled to the second mating portion102 b about a pivot pin 42 such that the jaw members 32, 34 arepivotable to a closed configuration (FIG. 3) where the jaw members 32,34 are closer together to clamp the tissue therebetween. The jaw members32, 34 include respective proximal drive flanges 44, 46 extending intothe second mating portion 102 b, where the proximal drive flanges 44, 46engage a drive pin 48. The drive pin 48 is movably disposed in alongitudinal drive slot 50 extending through the second mating portion102 b. The drive pin is operatively associated with the movable handle26 (FIG. 1) through the separable coaxial joint 100 to reciprocatethrough the drive slot 50. Each of the proximal drive flanges 44, 46 ofthe jaw members 32, 34 include a respective cam slot 52, 54 that engagesthe drive pin 48 as the drive pin 48 reciprocates through thelongitudinal drive slot 50. The cam slots 52 and 54 are disposedobliquely with respect to the longitudinal drive slot 50 such thatlongitudinal movement of the drive pin 48 in the direction of arrows“B2” induce the jaw members 32, 34 to pivot about the pivot pin 42 inthe direction of arrows “B1.” This type of construction inducesbilateral jaw motion. Other unilateral constructions are also envisionedin which only one of the jaw members 32, 34 moves with respect to theelongated shaft 16 to move between the open and closed configurations.

The pair of jaw members 32, 34 includes a pair of opposed electrodes 58,60 positioned to contact tissue situated between the jaw members 32, 34.The opposed electrodes 58, 60 are associated with opposite electricalpotentials (+), (−) to permit an electrosurgical current to flow throughthe tissue situated between the jaw members 32, 34. The electrosurgicalcurrent, when applied in conjunction with an appropriate amount ofpressure to the tissue, may effect a tissue seal. To form an effectivetissue seal, a relatively high clamping force is typically generated toimpart a closure pressure on the tissue in the range of from about 3kg/cm² to about 16 kg/cm². An appropriate gap distance of about 0.001inches to about 0.006 inches may be maintained between the electrodes 58and 60, although other gap distances are contemplated.

Referring now to FIG. 3, end effector 14 is depicted in a closedconfiguration wherein the upper and lower jaw members 32, 34 are closertogether than when in the open configuration. The drive pin 48 is movedto a proximal position in the drive slot 50 and cam slots 52, 54 toinduce the jaw members 32, 34 to pivot toward one another about pivotpin 42. In the closed configuration, the jaw members 32, 34 may apply aclamping force to tissue, and the electrodes may deliver electrosurgicalenergy to the tissue to generate a tissue seal. Thereafter, thereciprocating knife 40 may be advanced to transect the sealed tissuecaptured between the jaw members 32, 34.

The reciprocating knife 40 includes a sharp distal edge 62 and abifurcated proximal shank 64. The proximal shank 64 is operativelycoupled to the trigger 38 (FIG. 1) through separable coaxial joint 100as described below with reference to FIGS. 4 through 7. The trigger 38is operable to drive the knife 40 in a longitudinal direction “D1.” Thesharp distal edge 62 may be driven into a knife channel 68 defined ineach of the jaw members 32, 34, and thus, sealed tissue captured betweenthe electrodes 58, 60 may be transected. The knife 40 may be rotatedabout longitudinal axis A-A in the direction of arrows “C1” along withthe end effector 14, and thus, the knife 40 may be operable irrespectiveof the rotational orientation of the end effector 14.

Referring now to FIGS. 4 and 5, a distal end of elongated shaft 16defines first mating component 102 a. The first mating component 102 aincludes a structural, outer tubular member 106, a radiallyintermediate, proximal jaw drive shaft 108, and a central, proximalknife drive rod 110. The outer tubular member 106 may be fixedly coupledto stationary handle 24 (FIG. 1) and thus provides a proximal stationaryreference structure for the relative motions of the proximal jaw driveshaft 108 and the proximal knife drive rod 110. Alternatively, in a“shaft rotation” embodiment (not shown) the outer tubular member 106 maybe fixedly coupled to an actuator configured to rotate relative to thestationary handle 24.

The proximal jaw drive shaft 108 is operatively coupled to the movablehandle 26 (FIG. 1) such that manipulation of the movable handle 26induces longitudinal motion of the proximal jaw drive shaft 108 relativeto the outer tubular member 106 in the direction of arrows “B3.” Theproximal jaw drive shaft 108 is also operatively coupled to the rotationknob 36 such that manipulation of the rotation knob 36 inducesrotational motion of the proximal jaw drive shaft 108 relative to thestationary outer tubular member 106 in the direction of arrows “C2 a.”In an alternative “shaft rotation” embodiment (not shown) the outertubular member 106 may be induced to rotate in the direction of arrows“C2 b.” The proximal knife drive rod 110 is operatively coupled to thetrigger 38 (FIG. 1) such that manipulation of the trigger 38 induceslongitudinal motion of the proximal knife drive rod 110 in the directionof arrows “D2.” The proximal knife drive rod 110 is longitudinallymovable with respect to the proximal jaw drive shaft 108, but maymaintain a rotational orientation with respect to the proximal jaw driveshaft 108. The proximal knife drive rod 110 may be keyed to the jawdrive shaft 108 such that rotational motion of the proximal jaw driveshaft 108 in the direction of arrows “C2 a” induces a correspondingrotational motion of the proximal knife drive rod 110 in the directionof arrows “D3.” In other embodiments, the proximal jaw drive shaft 108and proximal knife drive rod 110 may be independently rotatable withrespect to one another.

Each of the outer tubular member 106, proximal jaw drive shaft 108 andproximal knife drive rod 110 exhibits an undercut profile at the distalend thereof. This profile permits each component 106, 108, 110 of thefirst mating component 102 a to interlock with respective correspondingcomponent of the second mating component 102 b (see FIG. 5). Forexample, the outer tubular member 106 of the first mating component 102a interlocks with the outer tubular member 104 of the second matingcomponent 102 b. The outer tubular member 106 exhibits an undercutprofile as exemplified by a laterally prominent distal hook portion 106a and a laterally indented, recessed or undercut hook receiving portion106 b. A laterally prominent hook portion 104 a of the outer tubularmember 104 may be received in the hook receiving portion 106 b, and ahook receiving portion 104 b of the outer tubular member 104 may receivethe hook portion 106 a of outer tubular member 106. When thus engaged,the outer tubular members 104, 106 are axially aligned about thelongitudinal axis A-A, and resist longitudinal separation because of theinterlocking hook portions 104 a, 106 a. However, the outer tubularmembers 104, 106 are susceptible to lateral separation as described ingreater detail below.

Inner drive members 108, 110, 112, 114 of first and second matingcomponents 102 a and 102 b also exhibit interlocking undercut profiles.For example, the proximal jaw drive shaft 108 interlocks with a distaljaw drive shaft 112 and the proximal knife drive rod 110 interlocks witha distal knife drive rod 114. This interlocking arrangement permits themotions the proximal jaw drive shaft 108 and proximal knife drive rod110 of the first mating component 102 a to be transmitted the distal jawdrive shaft 112 and distal knife drive rod 114 of the second matingcomponent 102 b. Additional inner members (not shown) may be provided inother embodiments to provide additional functionality to the endeffector 14 by enabling additional independent movements to betransmitted between the handle assembly 12 and the end effector 14.

The undercut profile of the inner drive members 108, 110, 112, 114 isexemplified by the proximal jaw drive shaft 108 as depicted in FIG. 4.The interlocking portion of the proximal jaw drive shaft 108 includes alaterally prominent, distal hook portion 120 and a laterally indented,proximal hook receiving portion 122. The hook receiving portion 122 isundercut with respect to the hook portion 120 in that the hook receivingportion 122 is less prominent laterally than the hook portion 120. Thehook receiving portion 122 includes a floor surface 124 that lies in aplane parallel to the longitudinal axis A-A, and pair of wall surfaces126 and 128 that lie in planes perpendicular to the longitudinal axisA-A.

The floor surface 124 is arranged to transfer torque to the distal jawdrive shaft 112 as the proximal jaw drive shaft 108 is rotated in thedirection of arrows “C2 a.” The wall surfaces 126 and 128 are arrangedto transfer compressive and tensile loads respectively to the distal jawdrive shaft 112 as the proximal jaw drive shaft 108 is translated in thedirection of arrows “B3.” A hook portion 132 of the second jaw driveshaft is configured to engage the floor surface 124 and wall surfaces126, 128 of the proximal jaw drive shaft 108 when the proximal anddistal jaw drive shafts 108, 112 are interlocked (see FIG. 6). The hookportion 132 may thus receive the longitudinal and rotational mechanicalforces for driving the jaw members 32, 34. Specifically, the compressiveand tensile loads may be transmitted to the drive pin 48 to open andclose the jaw members 32, 34, and the torsional loads may be transmittedto the end effector 14 to rotate the end effector 14 in the direction ofarrows “C1” as described above with reference to FIGS. 2 and 3.

Electrical connectivity may also be established by interlocking thefirst and second jaw drive shafts 108, 112. The proximal jaw drive shaft108 includes an electrically conductive pin 136 protruding from a distalend thereof and an electrically conductive pin-receiving slot 138 on alateral side thereof. The pin 136 and slot 138 may be electricallycoupled to opposite poles (+), (−) of the generator 18 (FIG. 1). Theslot 138(−) is configured to receive an electrically conductive pin140(−) protruding from a proximal end of the distal jaw drive shaft 112.The electrically conductive pin 140(−) is in electrical communicationwith electrode 60(−). Thus, by establishing electrical communicationbetween the slot 138 and the pin 140, electrical connectivity may beestablished between the electrode 60 and the generator 18. Similarly,the pin 136 may be electrically coupled to a slot 142 defined in thedistal jaw drive shaft 112 to establish electrical continuity betweenelectrode 58(+) and the generator 18.

The proximal knife drive rod 110 also exhibits an undercut profile thatallows the proximal knife drive rod 110 to transmit torsional,compressive and tensile loads to the distal knife drive rod 114 of thesecond mating component 102 b. The proximal knife drive rod 110 includesa floor surface 148 for transmitting torsional loads and wall surfaces150, 152 for transmitting compressive and tensile loads. The proximalknife drive rod 110 is operatively coupled to the trigger 38 (FIG. 1)and the distal knife drive rod 114 is operatively coupled to the knife64. Thus, interlocking first and second knife drive rods 110, 114operatively couples the knife 64 with the trigger 38.

Referring now to FIGS. 5 through 7B, a procedure for interlocking thefirst and second mating components 102 a, 102 b is described. First, theproximal jaw drive shaft 108 and proximal knife drive rod 110 are movedlongitudinally to a mating location with respect to the outer tubularmember 106 as depicted in FIG. 5. An appropriate longitudinal matinglocation is where the inter-engaging mating portion of the proximal jawdrive shaft 108 is generally aligned with the inter-engaging matingportion of the proximal tubular member 106 such that the laterallyprominent hook portion 120 and laterally indented hook receiving slot122 are exposed on an open lateral side of the tubular member 106. Inthis mating position, the laterally prominent portions of the proximaljaw drive shaft 108 and proximal knife drive rod 110 are aligned withthe laterally indented portions of the distal jaw drive shaft 112 anddistal knife drive rod 114 respectively, and the laterally prominentportions 160 a of the outer tubular member 106 are aligned with thelaterally indented portions 104 b of the outer tubular member 104.

The movable handle 26 and the trigger 38 (FIG. 1) may be employed tomove the proximal jaw drive shaft 108 and first knife drive shaft may bemoved to the mating position. Various mechanisms such as detents orother indicators may be incorporated into the actuators 26, 38 toprovide a tactile indication that the mating location has been achieved.The mating location may be achieved by moving the actuators to alocation outside the range of motion required for normal use of theinstrument 10. Similarly, a rotational orientation of the proximal jawdrive shaft 108 and proximal knife drive rod 110 may be achieved usingrotation knob 36. The mating rotational orientation is characterized inthat the pins 136, 140 align with the respective slots 142, 138.

When an appropriate mating location and orientation is achieved, thefirst and second mating portions 102 a, 102 b may be approximated in alateral direction indicated by arrows “E1” and “E2” in FIG. 5 to theengaged configuration of FIG. 6. With this single lateral motion,simultaneously the outer tubular member 106 interlocks with the outertubular member 104, the proximal jaw drive shaft 108 interlocks with thedistal jaw drive shaft 112, the proximal knife drive rod 110 interlockswith the distal knife drive rod 114, and the pins 136, 140 engage therespective slots 142, 138. The configuration of FIG. 6, however, may becharacterized as an unlocked configuration. This is because the firstand second mating portions 102 a, 102 b may be laterally separated byapplying laterally directed forces to the first and second matingportions 102 a, 102 b in the relative directions of arrows “E3” and“E4.”

The first and second mating components 102 a, 102 b may be moved to alocked configuration as depicted in FIG. 7A, wherein the first andsecond mating components 102 a, 102 b resist separation from oneanother. The proximal jaw drive shaft 108 may be advanced distally untila portion of the proximal jaw drive shaft 108 extends into outer tubularmember 104 of the second mating component 102 b. This arrangement causesinterference between the proximal jaw drive shaft 108 and the outertubular member 104, prohibiting the separation of the first and secondmating components 102 a, 102 b in the lateral direction of arrows “E3”and “E4.” The movable handle 26 (FIG. 1) may again be employed toadvance the proximal jaw drive shaft 108 to the locked position of FIG.7A. Alternatively, the proximal jaw drive shaft 108 may be retractedproximally until the proximal jaw drive shaft 108 and a portion of thesecond jaw drive shaft 114 is drawn into the first mating component 102a to lock the first and second mating components 102 a, 102 b.

Similarly, the proximal jaw drive shaft 108 may be rotated in thedirection of arrows “C2 a” to move the first and second matingcomponents 102 a, 102 b to the locked configuration depicted in FIG. 7B.In this locked configuration, the lateral direction in which the outertubular members 104, 106 tend to separate is dissimilar from the lateraldirection in which the first and second jaw drive shafts 108, 114 tendto separate. Thus, the first and second mating components 102 a, 102 bare positively locked since there is no lateral direction in which allinterlocking members of the first and second mating components 102 a,102 b will tend to separate. The rotation knob 36 may be employed torotate the proximal jaw drive shaft 108 into the locked configuration ofFIG. 7B.

Various other locked configurations are contemplated. For example, anadditional tubular member 170 (shown in phantom in FIG. 7B) may beplaced over the first and second mating components 102 a, 102 b toprohibit separation thereof. An inner diameter of the tubular member 170is slightly larger than an outer diameter of the outer tubular members104, 106. Also, a locked configuration may be achieved by translatingthe first knife rod 110 (FIG. 4). The trigger 38 may be employed toadvance the first knife rod 110 into the second jaw drive shaft 114, andthus create an interference that prohibits separation of the first andsecond mating components 102 a, 102 b. Any combination of translationand rotation of the proximal jaw drive shaft 108 and the first knife rod110 may be employed to move the first and second mating components 102a, 102 b from the unlocked mating configuration of FIG. 6 to a lockedconfiguration suitable for performing a surgical procedure. Followingthe procedure, the proximal jaw drive shaft 108 and the first knife rod110 may be returned to the unlocked configuration of FIG. 6 to permitde-mating of the first and second mating components 102 a, 102 b.

Referring now to FIG. 8, another embodiment of a separable coaxial joint200 is depicted with first and second mating components 202 a, 202 b ina locked configuration. The first and second mating components 202 a,202 b include outer tubular members 204, 206 each exhibiting an undercutprofile that permits the outer tubular members 204, 206 to interlockwith one another and resist longitudinal separation. First and secondjaw drive shafts 208, 212, and first and second knife rods 210, 214interlock to transmit rotational and longitudinal motion, and a pin 236engages slot 242 to transmit electrical energy between the first andsecond mating components 202 a, 202 b.

Outer tubular members 204, 206 exhibit a first outer diameter OD1 thatis sufficiently large to facilitate manual manipulation of the separablecoaxial joint 200 such that the first and second mating components 202a, 202 b may be laterally approximated by hand. The first outer diameterOD1 also provides robustness to the outer tubular members 204, 206 thatpermits the coaxial joint 200 to withstand the various loads that maytend to separate first and second mating components 202 a, 202 b. Insome applications, it may be advantageous for portions of an elongatedshaft to exhibit an outer diameter OD2 that is smaller than the firstouter diameter OD1. For example, the portions of an elongated shaft thatenter a surgical field in an endoscopic procedure may be configured witha smaller outer diameter OD2 to permit the procedure to be performedthrough a smaller incision.

Outer tubular member 204 is fixedly coupled to a shaft portion 260extending proximally therefrom. The shaft portion 206 exhibits thesmaller outer diameter OD2 and may couple the outer tubular member 204to a reusable handle assembly of a surgical instrument. The outertubular member 204 is fixedly coupled to a shaft portion 262 extendingdistally therefrom. The shaft portion 262 exhibits the smaller outerdiameter OD2 and may couple the outer tubular member 204 to a modularend effector. A first jaw drive tube 264 extends slidably through theshaft portion 260, and may couple the proximal jaw drive shaft 208 to anactuator. A second jaw drive tube 266 extends slidably through the shaftportion 262, and may couple the second jaw drive shaft 212 to a jawmember on the end effector. Thus, the jaw drive tube 264 may betranslated and rotated to induce a corresponding translation androtation of first and second jaw drive shafts 208, 212 and the secondjaw drive tube 262. The outer tubular members 204, 206 providesufficient clearance for the first and second jaw drive shafts 208, 212to translate through a distance of G1 and G2. This distance issufficient to provide functionality to an end effector such as openingand closing a pair of jaw members.

Although the foregoing disclosure has been described in some detail byway of illustration and example, for purposes of clarity orunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the appended claims.

What is claimed is:
 1. A surgical instrument, comprising: a handleassembly supporting an actuator thereon; a proximal drive memberdefining a longitudinal axis, the proximal drive member operativelycoupled to the actuator such that manipulation of the actuator induceslongitudinal movement of the proximal drive member relative to thehandle assembly, the proximal drive member including a mating portionadjacent a distal end thereof; a distal drive member including a matingportion adjacent a proximal end thereof configured to selectively engagethe mating portion of the proximal drive member; an end effectoroperatively coupled to the distal drive member and configured formanipulating tissue; and a knife assembly including a knife, a distalknife rod, and a proximal knife rod, the distal knife rod operativelycoupled to the knife and configured to translate the knifelongitudinally, the distal knife rod including a mating portion, theproximal knife rod including a mating portion configured to selectivelyengage the mating portion of the distal knife rod.
 2. The surgicalinstrument according to claim 1, further comprising a proximal shaftmember co-axially disposed with respect to the proximal drive member. 3.The surgical instrument according to claim 2, further comprising adistal shaft member co-axially disposed with respect to the distal drivemember.
 4. The surgical instrument according to claim 3, wherein theproximal shaft member includes a mating portion adjacent a distal endthereof, and wherein the distal shaft member includes a mating portionadjacent a proximal end thereof configured to engage the mating portionof the proximal shaft member.
 5. The surgical instrument according toclaim 4, wherein the proximal drive member is movable relative to thedistal drive member between an unlocked configuration and a lockedconfiguration.
 6. The surgical instrument according to claim 5, whereinwhen the proximal drive member is disposed in the unlockedconfiguration, the mating portion of the proximal drive member isgenerally aligned with the mating portion of the proximal shaft memberto permit simultaneous lateral disengagement between the proximal shaftmember and the distal shaft member, and between the proximal drivemember and the distal drive member.
 7. The surgical instrument accordingto claim 6, wherein when the proximal drive member is in the lockedconfiguration, the mating portion of the proximal drive member islongitudinally offset with respect to the mating portion of the proximalshaft member to prohibit lateral disengagement between the proximalshaft member and the distal shaft member, and between the proximal drivemember and the distal drive member.
 8. The surgical instrument accordingto claim 1, wherein the proximal drive member is movable from anunlocked configuration where lateral engagement and disengagementbetween the mating portion of the proximal drive member and the matingportion of the distal drive member is permitted, and a lockedconfiguration where lateral disengagement between the mating portion ofthe proximal drive member and the mating portion of the distal drivemember is prohibited.
 9. The surgical instrument according to claim 8,wherein the actuator is operable to move the proximal drive memberbetween the locked configuration and the unlocked configuration.
 10. Thesurgical instrument according to claim 9, wherein the actuator isoperable to move at least a portion of the end effector relative toanother portion of the end effector.
 11. The surgical instrumentaccording to claim 1, wherein the end effector includes a first jawmember and a second jaw member, at least one of the first jaw member orthe second jaw member pivotable relative to the other jaw member. 12.The surgical instrument according to claim 1, wherein the end effectorincludes an electrode disposed thereon adapted for deliveringelectrosurgical energy to tissue.